// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * isl28022.c - driver for Renesas ISL28022 power monitor chip monitoring
 *
 * Copyright (c) 2023 Carsten Spieß <mail@carsten-spiess.de>
 */

#include <linux/debugfs.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/regmap.h>

/* ISL28022 registers */
#define ISL28022_REG_CONFIG	0x00
#define ISL28022_REG_SHUNT	0x01
#define ISL28022_REG_BUS	0x02
#define ISL28022_REG_POWER	0x03
#define ISL28022_REG_CURRENT	0x04
#define ISL28022_REG_CALIB	0x05
#define ISL28022_REG_SHUNT_THR	0x06
#define ISL28022_REG_BUS_THR	0x07
#define ISL28022_REG_INT	0x08
#define ISL28022_REG_AUX	0x09
#define ISL28022_REG_MAX	ISL28022_REG_AUX

/* ISL28022 config flags */
/* mode flags */
#define ISL28022_MODE_SHIFT	0
#define ISL28022_MODE_MASK	0x0007

#define ISL28022_MODE_PWR_DOWN	0x0
#define ISL28022_MODE_TRG_S	0x1
#define ISL28022_MODE_TRG_B	0x2
#define ISL28022_MODE_TRG_SB	0x3
#define ISL28022_MODE_ADC_OFF	0x4
#define ISL28022_MODE_CONT_S	0x5
#define ISL28022_MODE_CONT_B	0x6
#define ISL28022_MODE_CONT_SB	0x7

/* shunt ADC settings */
#define ISL28022_SADC_SHIFT	3
#define ISL28022_SADC_MASK	0x0078

#define ISL28022_BADC_SHIFT	7
#define ISL28022_BADC_MASK	0x0780

#define ISL28022_ADC_12		0x0	/* 12 bit ADC */
#define ISL28022_ADC_13		0x1	/* 13 bit ADC */
#define ISL28022_ADC_14		0x2	/* 14 bit ADC */
#define ISL28022_ADC_15		0x3	/* 15 bit ADC */
#define ISL28022_ADC_15_1	0x8	/* 15 bit ADC, 1 sample */
#define ISL28022_ADC_15_2	0x9	/* 15 bit ADC, 2 samples */
#define ISL28022_ADC_15_4	0xA	/* 15 bit ADC, 4 samples */
#define ISL28022_ADC_15_8	0xB	/* 15 bit ADC, 8 samples */
#define ISL28022_ADC_15_16	0xC	/* 15 bit ADC, 16 samples */
#define ISL28022_ADC_15_32	0xD	/* 15 bit ADC, 32 samples */
#define ISL28022_ADC_15_64	0xE	/* 15 bit ADC, 64 samples */
#define ISL28022_ADC_15_128	0xF	/* 15 bit ADC, 128 samples */

/* shunt voltage range */
#define ISL28022_PG_SHIFT	11
#define ISL28022_PG_MASK	0x1800

#define ISL28022_PG_40		0x0	/* +/-40 mV */
#define ISL28022_PG_80		0x1	/* +/-80 mV */
#define ISL28022_PG_160		0x2	/* +/-160 mV */
#define ISL28022_PG_320		0x3	/* +/-3200 mV */

/* bus voltage range */
#define ISL28022_BRNG_SHIFT	13
#define ISL28022_BRNG_MASK	0x6000

#define ISL28022_BRNG_16	0x0	/* 16 V */
#define ISL28022_BRNG_32	0x1	/* 32 V */
#define ISL28022_BRNG_60	0x3	/* 60 V */

/* reset */
#define ISL28022_RESET		0x8000

struct isl28022_data {
	struct regmap		*regmap;
	u32			shunt;
	u32			gain;
	u32			average;
};

static int isl28022_read_in(struct device *dev, u32 attr, int channel, long *val)
{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;
	u16 sign_bit;

	switch (channel) {
	case 0:
		switch (attr) {
		case hwmon_in_input:
			err = regmap_read(data->regmap,
					  ISL28022_REG_BUS, &regval);
			if (err < 0)
				return err;
			/* driver supports only 60V mode (BRNG 11) */
			*val = (long)(((u16)regval) & 0xFFFC);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	case 1:
		switch (attr) {
		case hwmon_in_input:
			err = regmap_read(data->regmap,
					  ISL28022_REG_SHUNT, &regval);
			if (err < 0)
				return err;
			switch (data->gain) {
			case 8:
				sign_bit = (regval >> 15) & 0x01;
				*val = (long)((((u16)regval) & 0x7FFF) -
					(sign_bit * 32768)) / 100;
				break;
			case 4:
				sign_bit = (regval >> 14) & 0x01;
				*val = (long)((((u16)regval) & 0x3FFF) -
					(sign_bit * 16384)) / 100;
				break;
			case 2:
				sign_bit = (regval >> 13) & 0x01;
				*val = (long)((((u16)regval) & 0x1FFF) -
					(sign_bit * 8192)) / 100;
				break;
			case 1:
				sign_bit = (regval >> 12) & 0x01;
				*val = (long)((((u16)regval) & 0x0FFF) -
					(sign_bit * 4096)) / 100;
				break;
			}
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int isl28022_read_current(struct device *dev, u32 attr, long *val)
{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;
	u16 sign_bit;

	switch (attr) {
	case hwmon_curr_input:
		err = regmap_read(data->regmap,
				  ISL28022_REG_CURRENT, &regval);
		if (err < 0)
			return err;
		sign_bit = (regval >> 15) & 0x01;
		*val = (((long)(((u16)regval) & 0x7FFF) - (sign_bit * 32768)) *
			1250L * (long)data->gain) / (long)data->shunt;
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int isl28022_read_power(struct device *dev, u32 attr, long *val)
{
	struct isl28022_data *data = dev_get_drvdata(dev);
	unsigned int regval;
	int err;

	switch (attr) {
	case hwmon_power_input:
		err = regmap_read(data->regmap,
				  ISL28022_REG_POWER, &regval);
		if (err < 0)
			return err;
		*val = min(div_u64(51200000ULL * data->gain * regval,
				   data->shunt), LONG_MAX);
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int isl28022_read(struct device *dev, enum hwmon_sensor_types type,
			 u32 attr, int channel, long *val)
{
	switch (type) {
	case hwmon_in:
		return isl28022_read_in(dev, attr, channel, val);
	case hwmon_curr:
		return isl28022_read_current(dev, attr, val);
	case hwmon_power:
		return isl28022_read_power(dev, attr, val);
	default:
		return -EOPNOTSUPP;
	}
	return 0;
}

static umode_t isl28022_is_visible(const void *data, enum hwmon_sensor_types type,
				   u32 attr, int channel)
{
	switch (type) {
	case hwmon_in:
		switch (attr) {
		case hwmon_in_input:
			return 0444;
		default:
			break;
		}
		break;
	case hwmon_curr:
		switch (attr) {
		case hwmon_curr_input:
			return 0444;
		default:
			break;
		}
		break;
	case hwmon_power:
		switch (attr) {
		case hwmon_power_input:
			return 0444;
		default:
			break;
		}
		break;
	default:
		break;
	}
	return 0;
}

static const struct hwmon_channel_info *isl28022_info[] = {
	HWMON_CHANNEL_INFO(in,
			   HWMON_I_INPUT,	/* channel 0: bus voltage (mV) */
			   HWMON_I_INPUT),	/* channel 1: shunt voltage (mV) */
	HWMON_CHANNEL_INFO(curr,
			   HWMON_C_INPUT),	/* channel 1: current (mA) */
	HWMON_CHANNEL_INFO(power,
			   HWMON_P_INPUT),	/* channel 1: power (µW) */
	NULL
};

static const struct hwmon_ops isl28022_hwmon_ops = {
	.is_visible = isl28022_is_visible,
	.read = isl28022_read,
};

static const struct hwmon_chip_info isl28022_chip_info = {
	.ops = &isl28022_hwmon_ops,
	.info = isl28022_info,
};

static bool isl28022_is_writeable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case ISL28022_REG_CONFIG:
	case ISL28022_REG_CALIB:
	case ISL28022_REG_SHUNT_THR:
	case ISL28022_REG_BUS_THR:
	case ISL28022_REG_INT:
	case ISL28022_REG_AUX:
		return true;
	}

	return false;
}

static bool isl28022_is_volatile_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case ISL28022_REG_CONFIG:
	case ISL28022_REG_SHUNT:
	case ISL28022_REG_BUS:
	case ISL28022_REG_POWER:
	case ISL28022_REG_CURRENT:
	case ISL28022_REG_INT:
	case ISL28022_REG_AUX:
		return true;
	}
	return true;
}

static const struct regmap_config isl28022_regmap_config = {
	.reg_bits = 8,
	.val_bits = 16,
	.max_register = ISL28022_REG_MAX,
	.writeable_reg = isl28022_is_writeable_reg,
	.volatile_reg = isl28022_is_volatile_reg,
	.val_format_endian = REGMAP_ENDIAN_BIG,
	.cache_type = REGCACHE_MAPLE,
	.use_single_read = true,
	.use_single_write = true,
};

static int shunt_voltage_show(struct seq_file *seqf, void *unused)
{
	struct isl28022_data *data = seqf->private;
	unsigned int regval;
	int err;

	err = regmap_read(data->regmap,
			  ISL28022_REG_SHUNT, &regval);
	if (err)
		return err;

	/* print shunt voltage in micro volt  */
	seq_printf(seqf, "%d\n", regval * 10);

	return 0;
}
DEFINE_SHOW_ATTRIBUTE(shunt_voltage);

/*
 * read property values and make consistency checks.
 *
 * following values for shunt range and resistor are allowed:
 *   40 mV -> gain 1, shunt min.  800 micro ohms
 *   80 mV -> gain 2, shunt min. 1600 micro ohms
 *  160 mV -> gain 4, shunt min. 3200 micro ohms
 *  320 mV -> gain 8, shunt min. 6400 micro ohms
 */
static int isl28022_read_properties(struct device *dev, struct isl28022_data *data)
{
	const char *propname;
	u32 val;
	int err;

	propname = "shunt-resistor-micro-ohms";
	if (device_property_present(dev, propname)) {
		err = device_property_read_u32(dev, propname, &val);
		if (err)
			return err;
	} else {
		val = 10000;
	}
	data->shunt = val;

	propname = "renesas,shunt-range-microvolt";
	if (device_property_present(dev, propname)) {
		err = device_property_read_u32(dev, propname, &val);
		if (err)
			return err;
	} else {
		val = 320000;
	}

	switch (val) {
	case 40000:
		data->gain = 1;
		if (data->shunt < 800)
			goto shunt_invalid;
		break;
	case 80000:
		data->gain = 2;
		if (data->shunt < 1600)
			goto shunt_invalid;
		break;
	case 160000:
		data->gain = 4;
		if (data->shunt < 3200)
			goto shunt_invalid;
		break;
	case 320000:
		data->gain = 8;
		if (data->shunt < 6400)
			goto shunt_invalid;
		break;
	default:
		return dev_err_probe(dev, -EINVAL, "%s invalid value %u\n", propname, val);
	}

	propname = "renesas,average-samples";
	if (device_property_present(dev, propname)) {
		err = device_property_read_u32(dev, propname, &val);
		if (err)
			return err;
	} else {
		val = 1;
	}
	if (val > 128 || hweight32(val) != 1)
		return dev_err_probe(dev, -EINVAL, "%s invalid value %u\n", propname, val);

	data->average = val;

	return 0;

shunt_invalid:
	return dev_err_probe(dev, -EINVAL,
			     "renesas,shunt-resistor-microvolt invalid value %d\n",
			     data->shunt);
}

/*
 * write configuration and calibration registers
 *
 * The driver supports only shunt and bus continuous ADC mode at 15bit resolution
 * with averaging from 1 to 128 samples (pow of 2) on both channels.
 * Shunt voltage gain 1,2,4 or 8 is allowed.
 * The bus voltage range is 60V fixed.
 */
static int isl28022_config(struct isl28022_data *data)
{
	int err;
	u16 config;
	u16 calib;

	config = (ISL28022_MODE_CONT_SB << ISL28022_MODE_SHIFT) |
			(ISL28022_BRNG_60 << ISL28022_BRNG_SHIFT) |
			(__ffs(data->gain) << ISL28022_PG_SHIFT) |
			((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_SADC_SHIFT) |
			((ISL28022_ADC_15_1 + __ffs(data->average)) << ISL28022_BADC_SHIFT);

	calib = data->shunt ? 0x8000 / data->gain : 0;

	err = regmap_write(data->regmap, ISL28022_REG_CONFIG, config);
	if (err < 0)
		return err;

	return regmap_write(data->regmap, ISL28022_REG_CALIB, calib);
}

static int isl28022_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct device *hwmon_dev;
	struct isl28022_data *data;
	int err;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_BYTE_DATA |
				     I2C_FUNC_SMBUS_WORD_DATA))
		return -ENODEV;

	data = devm_kzalloc(dev, sizeof(struct isl28022_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	err = isl28022_read_properties(dev, data);
	if (err)
		return err;

	data->regmap = devm_regmap_init_i2c(client, &isl28022_regmap_config);
	if (IS_ERR(data->regmap))
		return PTR_ERR(data->regmap);

	err = isl28022_config(data);
	if (err)
		return err;

	debugfs_create_file("shunt_voltage", 0444, client->debugfs, data, &shunt_voltage_fops);

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
							 data, &isl28022_chip_info, NULL);
	if (IS_ERR(hwmon_dev))
		return PTR_ERR(hwmon_dev);

	return 0;
}

static const struct i2c_device_id isl28022_ids[] = {
	{ .name = "isl28022" },
	{ /* LIST END */ }
};
MODULE_DEVICE_TABLE(i2c, isl28022_ids);

static const struct of_device_id __maybe_unused isl28022_of_match[] = {
	{ .compatible = "renesas,isl28022"},
	{ /* LIST END */ }
};
MODULE_DEVICE_TABLE(of, isl28022_of_match);

static struct i2c_driver isl28022_driver = {
	.class		= I2C_CLASS_HWMON,
	.driver = {
		.name	= "isl28022",
	},
	.probe	= isl28022_probe,
	.id_table	= isl28022_ids,
};
module_i2c_driver(isl28022_driver);

MODULE_AUTHOR("Carsten Spieß <mail@carsten-spiess.de>");
MODULE_DESCRIPTION("ISL28022 driver");
MODULE_LICENSE("GPL");